In a school,there are $20$ teachers who teach mathematics or physics. Of these,$12$ teach mathematics and $4$ teach both physics and mathematics. How many teach physics?

The solution set of the system of equations $x + y = \frac{2\pi}{3}$ and $\cos x + \cos y = \frac{3}{2}$,where $x$ and $y$ are real,is:

$A$ contractor has two teams of workers,team $A$ and team $B$. Team $A$ can complete a project $P$ in $12$ days and team $B$ can complete $P$ in $36$ days. Team $A$ starts working on $P$ and team $B$ joins team $A$ after four days. Team $A$ is withdrawn after another two days and team $B$ is asked to double its efficiency. The number of additional days required for team $B$ to complete $P$ is

There is a group of $265$ persons who like either singing,dancing,or painting. In this group,$200$ like singing,$110$ like dancing,and $55$ like painting. If $60$ persons like both singing and dancing,$30$ like both singing and painting,and $10$ like all three activities,then the number of persons who like only dancing and painting is:

In a group of $400$ people,$250$ can speak Hindi and $200$ can speak English. How many people can speak both Hindi and English?

The probability of choosing at random a number that is divisible by $6$ or $8$ from among $1$ to $90$ is equal to